Ingredients
2 1/2 pounds skinless hake or cod
2 large eggs, beaten
1/3 cup plus 1/2 cup mayonnaise
1 1/2 cups fresh breadcrumbs
1/4 cup capers, coarsely chopped
1/4 cup minced fresh chives
Coarse salt
Pinch of cayenne pepper
2 tablespoons extra-virgin olive oil, plus more for brushing
2 tablespoons Dijon mustard
8 brioche buns, split
Quick-Pickled Red Onions
Watercress sprigs
Preparation
Cut fish into 1/4-inch pieces, then coarsely chop until it holds together. Mix with eggs, 1/3 cup mayonnaise, breadcrumbs, capers, chives, 1 teaspoon salt, and cayenne. Form into 8 patties, each about 3 1/2 inches in diameter. Refrigerate, covered, at least 1 hour and up to 8 hours.
Heat 1 tablespoon oil in a large, heavy skillet over medium-high. Cook 4 burgers, flipping once, until golden brown and cooked through, about 10 minutes. Repeat with remaining oil and burgers.
Combine remaining 1/2 cup mayonnaise and mustard. Brush split sides of buns with oil; lightly toast in skillet. Sandwich burgers in buns with mayonnaise mixture, red onions, and watercress.
